Dark Lines, Rectangular Stains on Indoor Walls or Ceilings Ghosting Stain FAQs

Thermal tracking stains Q&A

Hidden Damage Risk When Evaluating Indoor Stains FAQs

Could foundation problems cause thermal tracking?

Could foundation problems cause thermal tracking? 2024-06-13 by Phoebe

Mod reply:

@Phoebe,

I think most experience building scientists would say no to your question although I can think of some rather unlikely but possible circumstances in which foundation damage could contribute to thermal tracking stains, particularly if the damage caused higher moisture levels in the building such as a foundation crack that leaks water into a basement or crawl space.

In general we see thermal tracking where indoor dust or soot is deposited on cooler surfaces that usually mark the location of studs or rafters.

Continuing:

Another example of foundation damage that could contribute to ghosting or thermal tracking would be severe building movement that dislocated framing, windows or doors such that there were new air leaks in walls or ceiling cavities.

However both of these cases that I've described are so extreme that you would certainly see a significant building damage that would be a much higher priority.

And if you see ghosting or thermal tracking with no cracks or signs of building movement then my second example is not what's going on in your building.

Follow up:

@InspectApedia Publisher, I know with 100% certainty the foundation is cracked. My parents bought the house in 1992 and discovered the foundation was cracked when they replaced the carpet prior to moving in. Despite their discovery, they carried on as if the Grand Canyon wasn’t underneath the living room carpet. The house is in Arlington, Texas and miraculously survived an EF3 tornado in 2012. My mother is still in denial but I am very concerned about the structural integrity of the house.

Doors don’t close properly or they are impossible to open, faucets leak or do not work at all and very bizarre electrical issues. Examples - Power surges that have literally exploded light bulbs and ignited the sprinkler system control box & sent it flying across the garage.

Back to the thermal tracking, my mother thinks the solution is a coat of paint and having the 32 year old carpet steam cleaned. She is furious that I will not throw money down that hole.

Reply:

@Phoebe,

The important safety question to address is whether there is such serious damage that there is risk of sudden building collapse. If that's the case then the building may not even be safe to be inside.

Most foundation damage is not in that category.

But some structures such as a concrete block foundation that is badly bowed or brick structures with cracked bond courses could be indeed in danger of collapse.

Extreme movement can also damage not just plumbing but electrical wiring leading to other safety hazards.

I'm sure you understand that I can't make that assessment based simply on texting a few photos and that you need a competent on-site inspector to help address that question.

Foundation cracks range in seriousness from not urgent or even cosmetic to very serious.

In addition to bringing in a local foundation damage expert to help you, our article on

FOUNDATION DAMAGE SEVERITY ASSESSMENT

Will be of some help to you.

It would be of course helpful to see photos of your foundation inside and out.

Please keep me posted on what you are told and we may be able to offer additional advice.

 

I have the black markings at all registers in my ceiling!

Hi HELP!! I have been living with this unknown black stuff in my apartment for the last 4 years. I have the black markings at all registers in my ceiling. When u remove pictures from the walls it makes a perfect boarder where the picture was.

I also have the markings like what is shown on picture 2021-10-23. It outlines the ceiling and where the wall meets the top of the ceiling.

I also have the black lines from ceiling to floor on each piece of wood that is 16 inches apart. It gets in my cupboards, inside my refrigerator, and it really adheres to plastic items. My bleach bottle plastic bowels ect. U can see small black pieces of what has come out through the vents on the floor and counters and if u take your finger and run it down it’s like grease.

The management wants me to sign a paper that states I will not hold them responsible should something happen health wise. I do not know who to contact or if anything can be done. Looking forward to hearing back from u. Thanku. 2022-11-09 by Michelle Blackwell

Mod reply:

@Michelle Blackwell,

The first I went most important safety thing to check is whether or not there's gas fired heating equipment that's not working correctly and is producing soot. If that's happening there could be a dangerous carbon monoxide poisoning desert. So be sure you have working CO detectors and smoke detectors in your home.

Warped, wavy, soft floors, lumpy walls, ghosting stains, possible water damage

My husband and I are currently painting the inside of a friends manufactured home (1999) that they are selling

While working we noted some odd and concerning issue's.

First several areas of the floor are soft and wavy, the walls in the 2 small bedrooms are literally warped horizontally when painting with a roller it was like going over speed bumps, in the master bedroom and bath there are signs of severe ghosting on walls and ceilings where we can actually see the complete outline of the frame.

I personally believe there could be water or moisture damage.

Also it has taken at least 3 coats of premium paint with primer to cover even the walls with no visible sign of problems...the paint won't stick and this is an issue we have faced before where there was excess moisture in the walls.

I am not an expert by any means just going on past experience and have seen how water or moisture damage can get into a mobile or manufactured home undetected. I shared my thoughts and concerns with our friend and they were upset it seems with us for sharing and we only suggested looking into it.

are going to have an inspection done so can you give me suggestions on any particular type of inspection they should have done or even testing in the home for mold? Thank you from Washington State USA On 2019-06-27 by Lisa P

by (mod) - painting the inside of a manufactured home for sale: problems to avoid

As you suspect a moisture problem that makes sense to have a thorough Home Inspection performed.

The scope of that includes looking for leaks, moisture sources, moisture trap, and improper or blocked ventilation.

Watch out: drywall that has been wet may be mold-contaminated on the hidden side - some tests cuts as well as an inspection of the attic or under-roof space will be needed to evaluat the conditions there.

Don't continue renovating before diagnosing these problems as your work could be wasted and could have to be done over again.

Painting Over Ghosting Thermal Tracking Stains FAQs

Can I cover thermal tracking stains with paint?

My home is a cape built in 2002; the first floor ceilings in each room have ghostlines (see image) that seem to be getting worse (extending) as time goes on. My guess is this is caused by insulation and/or ventilation problems and/or damage from bats or mice in the second floor walls/crawlspace.

As I now live alone and am not likely to live many more years, I would like to paint the ceilings to temporarily cover the stains.

My questions are: (1) How long (approximately) would a proper paint job last before the ghostlines reappear? (2) Should I be worried about the ceiling starting to sag and possibly collapse? (3) I've read that inside humidity can contribute to such problems; how do I measure it? 2025-02-13 by John

Mod reply:

@John,

If your ceilings are dead flat then you don't have evidence of a sagging ceiling problem.

If you use a lacquer primer sealer you might get away with painting over stains rather than trying to clean first.

I can't say how long that paint job will last because I don't know what the soot source is in your building..

That's actually the first thing that you should check. If you have gas fired heating equipment that's producing suit that's particularly dangerous risking fatal carbon monoxide poisoning. So in addition to having that equipment checked you would be sure you had working carbon monoxide and smoke detectors properly installed, located and tested in your building.

If a suit source is from something else such as smoking that's a different issue.

About the damage to your insulation, I don't think that mouse or rodent damage in a building would be so uniform and extensive that would be likely that you would have the same type of thermal tracking or ghosting stains everywhere in your home.

So more likely you have a combination of a source and perhaps an indoor moisture source that are worth investigating.

Daniel Friedman

Follow up:

@InspectApedia Publisher,
Thanks so much for your detailed and prompt response.

Reply:

@John,

Your photo shows typical ghosting or thermal tracking just as we're discussing.

The causes and explanation are in our article GHOSTING DARK STREAKS or LINES: CAUSES (above on this page ).

Certainly you can paint over those lines as I discussed.

More detailed advice is at THERMAL TRACKING REMEDIES https://inspectapedia.com/interiors/Stain_Remove_Prevent.php

Watch out: remember that our first priority is safety. That's why it's important to assure that any heating equipment, gas or oil, is operating properly and that that's not the source of the stain particles.

Follow up:

@InspectApedia Publisher,

[Here is detail about John's ghosting lines question - sent by private email to the editor.]

I’m contacting you to see if you can give me assistance (pro bono or otherwise)
regarding my home issues. I am a senior citizen with limited income (SS only), but I’m
perfectly willing to pay for your services. My problem is I am completely incompetent in
such matters, and I really worry that I might be cheated or overcharged if I go to a
“reputable” contractor about it without understanding what I need to have done.

I have previously posted a comment on your site on February 12 th under “John”
(https://inspectapedia.com/interiors/Thermal_Tracking_Lines.php)

I appreciated your response. I finally found a reasonable contractor who was going to
clean and repaint the ceilings. However, he had seen the ghost lines before and when
he returned months later, he was concerned that the lines had extended further. So, he
said he would have to test for mold first, and that, if there was mold, he would have to
report it and the repair work would have to be done by someone else. This bothered
me because, although I agree that the ghost lines have extended the past year, there
are no other symptoms of mold.

There are some other factors that may be contributing to the problem. Firstly, I had a
problem with my heating system (oil) several years ago. The servicer was supposed to
order a part and complete the repair on a timely basis. I was away on business and the
servicer dropped the ball and never did the repair until I discovered soot totally
blackening the side of my house where the heating vent is (no chimney). They
reluctantly agreed to wash the siding and did a reasonable but not perfect job.
However, there was also clear evidence of the soot permeating my basement and who
knows where else. I remember seeing a large amount of soot under the door at the top
of the basement stairs. I probably should have gotten a lawyer and made sure that all
the damage was remediated, but I didn’t. And, I never connected it to the ghost lines
because I thought that the stains were above the ceiling, not below. As I said before,
I’m incompetent in these areas.
Secondly, I have a poor exhaust fan for my kitchen stove. The large burners are all in
the front of the stove, and the fan does not (imo) extend out far enough or is not strong
enough to work properly. I have a smoke alarm down the hallway from the kitchen
which used to go off frequently from just normal cooking. I’m so paranoid about it now
that I watch it carefully and the alarm doesn’t go off very often but I can see the smoke
drifting around the kitchen and into my living room (one area where there are ghost
lines).
Thirdly, I have been alone in the house for several years now, and when I was working I
was constantly traveling and did not do anywhere near a proper job of dusting.

Even now, I am retired but have physical ailments that make me reluctant to put in the
necessary efforts.

One other thing comes to mind that may or may not be related. Towards the end of last
winter, I had ice damming on the front side of the roof; no water came into the house to
my knowledge, but the dam looked pretty severe. I had icicles on that side in previous
winters but I never observed damming. I have heating cables on the other side of the
roof because when I first moved here (only 3 years after the house was built), there
were very thick icicles (there still are if I neglect to plug in the heating cables). I do
know from experience in northern NH that damming can be caused by a specific set of
weather conditions, but I would like to resolve that problem as well before the winter
comes.

I greatly appreciate any assistance you can give me.

Reply:

@John,

I'm sorry to say that paid or pro bono, I can't be smart enough, based merely on a text of your observations, to make a complete and accurate diagnosis of your home or to say what it needs.

In my experience, which now extends over quite a few decades, 100% of the time that I've gone to a home after someone has described a concern, I have found additional important information that simply wasn't obvious to someone who hasn't spent their life around this type of diagnosis.

Reading the articles that you have at inspectApedia on thermal tracking or ghosting will help you understand that issue, it will help you determine whether a contractor or inspector you are speaking with understands the topic themselves, and it should make clear that thermal tracking is completely distinct from mold and growth pattern, texture, etc. Of course if if you've any doubt you can take the tape sample of mold or surface zoot or dirt on a surface and have that examined and identified by a lab

The only relation between mold and soot might be a high moisture level.

You certainly wouldn't expect to find mold growing in regular patterns mapping the spacing of framing members over large areas in various rooms, details that are characteristic of ghosting.

So if you don't see mold anywhere in the home and don't smell mold and if an inspection of the attic side of the ceiling drywall doesn't find mold then that's the end of that topic.

It would make sense to review the amount of insulation in your attic and walls, to look for air bypass leaks, and of course from a safety concern, to be sure that your heating equipment
Is working safely. If it's producing soot at good also be unsafe as well as unreliable. That's especially true with gas systems but it can be true for oil fired equipment as well. You might find a home inspector who's experienced with thermal tracking or ghosting if you need help assessing insulation, drafts, Heat loss, abnormal moisture levels indoors, or improperly functioning heating system.

An on-site inspector would look at the whole building to understand how it works, air movement, insulation, moisture, soot sources, Etc. Meanwhile don't do any expensive repairs before you have a more confident diagnosis. Keep me informed.

If there are typos or spelling errors forgive me but I'm dictating this message through my phone as I'm out of our lab.

Daniel Friedman

Follow up:

@InspectApedia Publisher,

I followed your advice (many thanks) and have a home inspector/"renovation consultant" coming here tomorrow to assess my situation. In advance of that, I'm wondering if you can answer a question for me.

The ghost lines have clearly lengthened over the years, and I'm wondering why.

If the coolest spot is in point A, for example, why doesn't ALL the soot or dust continue to accumulate there?

Does the prior accumulation make it less of a cold spot so the soot/dust that comes later so it seeks the next coolest point?

John

Reply:

@John,

​Dust is rather uniform in building air, principally affected by the rate, volume, and direction of air movement in the building. So any variation in surface temperature that corresponds (usually) with variation in surface moisture, will cause variation in dust that is deposited or sticks in that area.

So what's probably happening in your house is that some dust IS being deposited atop the shorter, earlier thermal tracking or ghosting lines while more deposits along the greater length of the damp or cooler area that probably marks the location of a ceiling joist, rafter, or wall stud, or a gap in insulation.

Will black ghosting stains in our home in Australia reappear after we clean and paint the stained surfaces?

I just read your article on Thermal Tracking, Bridging and Ghosting, and believe I may have this problem in my home.

I've had several builders around to look, and none of them have ever seen anything like it.

We've owned the house for 3 years now, and it seems to have started around winter last 2015 (I live in Australia so May/June). We don't have any open fireplaces or anything, just 2 reverse cycle air conditioners.

We recently cleaned out the filters on the living room air conditioner and it was filthy, so I was wondering if they may have been contributing to the problem. The house was poorly insulated, however I insulated the entire ceiling around June of 2015.

I recently cleaned some areas of the house with sugar soap and warm water, and the marks appear to come off, or just smudge around the wall/ceiling. Are you able to tell me what you think the problem might be, and the solutions to fixing it.

It seems to be slowly spreading to other areas of the house also. We were going to repaint the ceiling and walls, but I just want to know what this is and if it will come back again after I've repainted it. - T.D. 2016/01/03

Reply: Yes stains will recur until we correct the causes of thermal tracking or ghosting

Yes the chimney effect caused by the holes cut into a ceiling to mount pot lights (recessed ceiling lights) will increase the air movement around and up through each light, increasing deposits of building dust and soot thereon. But the root causes of thermal tracking remain those listed at the top

of GHOSTING DARK STREAKS or LINES: CAUSES

For a guide to cleaning, covering, painting, and preventing these indoor stains on walls and ceilings please see

THERMAL TRACKING REMEDIES for details

Watch out: I agree that you don't want to insulate over recessed lights if they are not rated for that application as doing so can cause overheating or even a fire; and changing all of the recessed lights to those rated for direct contact in an insulated ceiling (DCIC) so that they can be insulated over is a desirable improvement but not a cheap one.

But if we don't correct the causes of thermal tracking or ghosting it will return after cleaning and painting.

Reader follow-up:

I've been up in the roof today, and there are areas around the downlights that aren't insulated, but they've been left there so that we don't start a fire in the roof from the insulation coming into contact with a hot surface.

I will have to look at some heat shields for the downlights so we can insulate the entire area.

Another interesting thing, which I think could be a definite problem is the exhaust fan duct from the kitchen goes into the ceiling but doesn't go any further, so any hot, fatty, humid air from Cooking goes into the ceiling but can't escape.

Could this be coming back down through the holes for the downlights and sticking to the ceiling causing these marks?

The downlights do have a black sticky residue around them that spreads when touched with a wet cloth.

Reply:

Watch out: Venting a kitchen exhaust into a ceiling not to outside is unsafe and probably violates your local building codes. Over time the accumulation of grease can cause a building fire. I would stop using the fan entirely until it can be vented to the outdoors.

You typically need 3" of clear un insulated space around the ceiling pot lights but the light fixture should contain a label with the specific clearance distance for insulation; Those large dark rectangles on the ceiling suggest large cold areas of missing or incomplete insulation.

If it were my home I'd change over to DCIC rated lights that can be covered by insulation.

Insulation leaks & thermal bypass defects:

We use thermal tracking marks on an area where insulation is visible to identify and correct air bypass leaks, thus saving energy or reducing home heating or air conditioning costs.

Details about air leaks in buildings are discussed

at AIR BYPASS LEAKS.

Building air leak testing is described

at BLOWER DOORS & AIR INFILTRATION

and at AIR LEAK DETECTION TOOLS.

Insulation adequacy: Clues that suggest Insulation adequacy can be picked up easily if the observer will use thermal tracking marks on larger areas of interior walls or ceilings to tell us areas of the building that are not insulated, or are not well insulated - areas where we should consider adding or improving insulation to save energy by reducing building heating or cooling costs.

See INSULATION INSPECTION & IMPROVEMENT for more information.

Usually soot marks, thermal bridging, or thermal tracking stains appear, if at all, in the building interior locations listed just below discussed in the remaining sections of this article.

Ghosting Stains & Missing Insulation FAQs

Is wall gap or air leak causing my ceiling stains or carbon?

Hi there, I both a house in July 2018 and noticed there was black all around the edges of the carpet and the baseboards. The carpet guys said that all houses have carbon and that since this carpet was white it just shows more and was old. At the same time, I noticed black in the ceilings mostly in one section of the house a living room with cathedral ceiling and an office right next to the living room.

I researched this in great detail and ultimately thought the guy had run the fireplace with the vent closed or something. I tried to wipe it down but it mostly just moved around. Ultimately in the flurry of activity our painter primed it (he says) and then painted. Life was pretty hectic then and out of sight out of mind I have been slaying bigger dragons.

Now I feel like I see the black coming back in the upstairs and many rooms right where the ceiling meets the top of the wall. Sometimes it is faint and I think am I seeing things? I keep seeing it over and over and am so afraid my newly painted walls are going to be ruined so I set out to research and found your wonderful and amazingly informative page (THANK YOU)!

I am not mechanically inclined but have been reading and reading and I see many of the images seem to form pattern that match the framework behind the walls, I do not have that. Only where the ceiling and upper part of the wall meet. Even when I noticed it before move in, it was not those types of marks but it was in much greater abundance in the ceiling/upper wall then.

One thing I wondered as I try to decipher all the information here is all the cold air returns are at the top of the wall almost at the ceiling and I have never seen that before and not sure if that is a contributor.

OK so I went back through my phone to find the pictures I took when I bought the house and wow it was a lot worse than I guess I remember. I am attaching the pictures I have of the living room ceiling (two can lights) and the office which was much worse than I remember! I can try to get a picture of what I am seeing now but guessing that is not relevant, whatever the problem is, it is...

It will only let me upload one picture here, I have more I can send if needed. 2019-01-13 by Karen

Mod reply:

Well I'm not sure I agree with the guys who said to you all houses have carbon.

It's true that all houses have house dust. And it's also true that house just gets deposited on surfaces.

However when you see a specific pattern such as the one you described, I suspect there is an air leak, probably from below, that is moving house dust or other dust through a floor or Wall Gap or air leak.

Take a look to be sure that you don't have a source of actual soot, such such as an unsafe or improperly operating gas or oil burner.

Then look carefully below the floor in question to see if you can see an air leak or Gap there.
You can also look above it but you'll have to lift the carpet along the wall.

Let me know what you find or send me a photo of any gaps and we can discuss solutions.

Note: your image needs to be in a form that the comment box software will handle. Those include most common image formats such as .jpg .gig .img but not document or PDF files.

I recently noticed these dark streaks of soot like marks on my kitchen wall

I have recently noticed these dark streaks of soot like marks on my kitchen wall. They’ve only started coming recently and are getting more prominent. Over the last year the ceiling and walls have been painted and the dark marks weren’t there before either.

Can anyone advise please? Thanks. 2023-02-14 by Lou

Mod reply:

@Lou,

From just one photo, we don't know for sure. And we don't know where you're located - city, state, country - as that might give us some climate-related clues.

But some thoughts are:

The dark areas might be due to thermal tracking possibly related to inadequate insulation in the ceiling at the house eaves -particularly if all of the stains on ceilings are at / along exterior walls.

In that case, we may find inadequate ventilation under the roof eaves of the building along with an accumulation of snow or ice at the point of change in roof pitch. Either or both of those conditions could contribute to moisture or leaks in that area.

In turn, leaks from ice damming or accumulated snow in that area can dampen the ceiling that in turn invites accumulation of dust or soot stains.

Check the insulation in the attic; Also check that you have not had moisture or leaks in those ceiling areas due to ice dam leaks.

Has this only happened in winter when the heat is turned on? Warm air rises which may affect the building's air movement patterns and thereby alter the movement of any dust or other particles in the air.

What is that white piping for? Hot water, gas? The staining seems to follow those runs.

Keep us posted.

How can I fix these ghosting or thermal tracking lines and rectangles on ceilings - not from a roof leak

Hi, I have noticed this strange rectangular stain on my vaulted ceiling recently. I noticed these on a dry day ( no rain for few days). I believe the humidity inside the house was high as no AC was on for 10/15 days.

Could this be thermal tracking? Also when I tried touching those area in a hot sunny day, I felt some points felt warm to touch then the rest of the ceiling.

Same area I touched after a heavy rain, didn’t felt wet, but it didn’t felt warm that day. Any idea if it is due to missing or insufficient insulation on vaulted ceiling?

How can I fix these dark ceiling stains? Who can check if it is an air leak? The roofer after seeing this confirmed that it is not a roof leak and suggested to get it painted.

Reply by (mod) - add missing insulation

Those look like thermal tracking or ghosting stains, associated with the combination of air leaks or voice and insulation and of course an indoor source of dust or switch or debris.

An inspection of the under-roof area will include looking for voids in the insulation, missing insulation, roof leaks, attic moisture, and mold contamination.

Even with no roof leaks or high indoor moisture, insulation voids alone combined with normal indoor dust levels and air movement can produce the ghosting stains in your photo. But those rectangular stains are about the same as the width between ceiling joists - I suspect insulation is thin or missing in those areas.

Please see THERMAL TRACKING REMEDIES for details -

and let me know if you have further questions.

Thermal Tracking Stains at Electrical Outlets FAQs

Diagnose black lines on walls above electrical receptacles

I have dark lines coming from above every plug socket and switch in the kitchen. They go up to the ceiling? On 2019-04-24 by Jon Robertshaw

Reply by (mod) -

Perhaps with some photos of the stains and some information about the building country, city (*thus climate), age, type of construction (wood frame, insulated wall cavities0 etc. one can make a useful diagnosis.

There could simply be air leaks at those receptacles, but

Watch out: black stains at electrical receptacles could indicate overheating electrical wires, unsafe connections, and a shock or fire hazard. So it's worth hangin an electrician examine one or more of those devices to assure there's no electrical hazard.

Kitchen stains are also often related to deposits of soot or grease or smoke or even just the effects of moisture from cooking. As in the article above, such deposits can mark stud locations.

Watch out: some indoor soot sources can indicate dangerous conditions, such as soot produced from improperly adjusted or vented gas burners.

At THERMAL TRACKING BRIDGING GHOSTING - home

you will read more explanation of how and why thermal tracking type stains appear on walls. Please take a look there and let me know what questions remain.

Ghosting Stains at Ceiling Lights FAQs

What are these dark stains around our ceiling lights?

We just moved in to this house, that is full of round patches.

Can someone Identity the problem. On 2018-02-01 by Alicia -

Reply by (mod) - thermal tracking or ghosting stains: air leaks around recessed ceiling lights - pot lights

Alicia

From your photo I would say it's pretty likely that those recessed ceiling lights have had insulation pulled-back (avoiding an overheating light fixture and fire hazard).

Air leaks are common around recessed ceiling lights and are worse when the opening cut for the light is not sealed against air leaks, and are exacerbated by the use of older ceiling lights that, for fire safety, can not be covered by attic insulation.

The result is a chimney effect that increases heat loss as well as a cool spot on the ceiling where moisture and dirt adhere - it's a good example of thermal tracking discussed in this article.

You show that the spots can appear not just in lines but in whatever pattern of cool area occurs in a ceiling or wall.

If this were my house I would consider installing DCIC-rated ceiling lights so that they can be safely insulated-over, and I would seal the light cutouts against air leakage.

See RECESSED LIGHT CLEARANCES

Thermal Tracking Stains & Roof Leak FAQs

Do thermal tracking stains always mean mold contamination of the roof was leaking?

If I have thermal streaks on the wall should I also assume that I have mold in back of the wall, since I have had a leaking roof which is now fixed? On 2016-06-17 by Laura

Reply by (mod) - roof leaks - mold risk

Thermal tracking does not mean that there is always mold contamination in the same area as the streaks; those are surface depositions of dust from temperature differences + slight moisture differences on the surface.

But

Watch out: if there was a roof leak that sent water into the wall cavity, that needs to be explored from above or by test cuts because mold contamination is quite likely.

Also any insulation over moldy drywall should be assumed to be moldy and will need to be removed, the surfaces cleaned before the insulation and drywall are restored.

Vehicle Exhaust & Ghosting Stains FAQs

Thermal tracking on garage ceiling caused by car exhaust?

Wow, what a great resource, thank you so much for all the info!

Question: Garage ceiling has this tracking at all the drywall seams.

I can see that the ceiling was insulated. Dark spots exactly correspond with the 12" joint compound finishing knife.

Could it be that the compound was simply not sealed properly when it was painted? Also, could exhaust from cars cause this-it's nowhere else in the house.

Thanks, I love this site! (Oct 2, 2014) Sam

Reply:

Sam

I don't think the stains are caused by poor sealing of the drywall seams.

More likely the drywall joints are over wall studs, pipes, or other (less-insulated) cooler surfaces that pick up a bit more moisture and thus particle deposits thus stains.

Yes car exhaust could be a particle source, also a moisture source. And if the car is burning oil and is left running for some time in the garage these effects would be increased.

Diesel exhaust probably produces higher levels of carbon and soot so might also be a factor in staining in garages.

Watch out: for potentially fatal carbon monoxide hazards if car exhaust can enter the home or accumulate in the garage.

Thermal Tracking Stains at Seaside Properties FAQs

Black stains by thermopherosis? by deionisation from sea spray?

A friend has black deposits appearing evenly on vertical surfaces at the top of an internal lounge wall, just under the coving. The wall-hung pictures also have severe dirt 'shadows'.

The appearance is similar to that I experienced when I had a de-ioniser in use in my bedroom, but there is none in the friend's lounge but there is a tv and modern wall-hung logfire-effect unit.

Heating is by conventional hotwater radiators. The house is right on the sea front (at Bude) and fully exposed to off-sea winds.

Could the cause be thermopherosis? Caused by deionisation from sea spray? Or what? And what might the solution be? No nearby pollution source that I can identify. (Jan 17, 2012) John Dabbs

Reply: role of sea salt (in air), ionization, or gas burners in indoor thermal tracking stains

John, if by "appearing evenly" you mean at even spaces or intervals such as marking the intervals of building framing members, that would be a classic diagnostic clue indicating thermal tracking.

And yes, using a "de-ioniser" (more likely it was an ionizer - a device that puts an electrical charge on dust particles, causing them to plate out on wall and other building surfaces) can contribute to soot and thermal dust tracking stains on building walls and ceilings.

I'm not sure of the role that off-sea winds would play in thermal tracking - it depends - for example on the effect of winds on building heat loss.

Sea spray itself sounds an unlikely cause of black stains to me as I don't imagine much sea spray actually enters the building interior.

However salt deposits on building surfaces might indeed act as a moisture absorber from damp sea air, increasing the moisture level of those surfaces that in turn increases the rate of dust deposition and thus increases thermal tracking stains.

Even common house dust will be enough of a particle source to explain thermal tracking in buildings, but where there are additional dust or particle sources the effects will appear more rapidly and at more extreme levels.

Examples include an oil burner that is not working properly, producing soot; use of candles, scented candles, woodstoves, fireplaces, or even burning cooking materials. Pets can also be contributors.

Watch out: a malfunctioning gas burner that is producing soot is very dangerous, risking fatal carbon monoxide poisoning so be sure any gas burning equipment has been checked by an expert.

The solution to thermal tracking includes:

- identify and remove sources of high levels interior dust or particulate debris as much as possible

- identify locations of building air leaks and heat losses and correct them

- add insulation, particularly where there are voids

- monitor and correct high levels of interior moisture

Reader follow-up:

Many thanks indeed, Dan, for your comments. Perhaps I should have said that the staining is "uniformly" spread ie a consistent level along the upper perimeter of the room, graduating in intensity as the ceiling is approached.

The wall construction is, I believe, solid masonry (I'll check that), and the effect is apparent on all walls whether internal or not. One wall - facing the sea - has a large double-glazed sliding patio door and a "soot" film appears on this after only a few days after cleaning.

Yes, I should have referred to an ioniser - I apologise! It was because of the similarity of this problem to my previous experience with one of these that I was wondering if this was due to an ionising effect somehow. Hence I was wondering if excessive sea spray could cause ionisation? Clutching at straws?

The household has a cat, but it's a large, open house. The room is clean with few furniture pieces, all modern, with a fitted carpet.

There are a few nearby properties, all as far as I know with natural gas heating.

Completely residential area, and I can't identify an probable sources of dirt/soot particles, but I'll have another look around.

No woodfires, candles or oil burners. Two of the walls have hot water radiators fixed to them, but the staining is at the same level on a third wall with no heating fixed to it.
Any further thoughts?

Ghosting Stains & Gas Stoves FAQs

Ghosting stains due to a gas stove in an all electric house?

We have a friend with a house that has ghosting at the 2nd floor ceiling and top 1-2' of wall where it meets the ceiling; the nails are also popping at this ceiling/wall juncture.

The house is entirely electric with exception of a gas fired stove in the lower level of the split level home.

Do you think the ghosting is due to a malfunction with the stove or some other issue? thank you Apr 7, 2012) sue white

Reply:

Not likely - but

Watch out: a gas cook stove that is making visible soot is not working properly and is unsafe, risking fatal carbon monoxide poisoning.

 

Ghosting Stains on Carpeting FAQs

Thermal tracking stains on carpet in the middle of a room?

Have you ever seen this in carpet in the middle of a room (not near the baseboards). I received a moisture meter to check some ceiling stains to see if they were active or inactive after the former owner replaced the roof. I was using the moisture meter to check the basement- all surfaces.

I found some areas in the basement carpet where the moisture meter was high but dry to the touch. I run a humidifier in that room and it doesn't work very hard to maintain 45-50 rh%

It has a 'line' type stain. A bit darkened (carpet is grey, so this is darkish grey), but not like the other areas where there is actual infiltration soiling (I have seen it is one room near the baseboards but is completely dry). My home is old, so of course it has air leaks.

The former owners had a couch over this area, so I thought it was due to that. Adjacent staining is yellow coloring and also shows moisture in the meter. So moisture and a line/ghosting in carpet. The carpet is gross anyway, so I thought about peeling it back to see if there is a crack in the slab (60+ yr old house).

A contractor friend, without seeing it, said it was radon gas escaping. That seemed like a stretch, since Radon is colorless. I think though, perhaps he meant, air is feeding through the crack and depositing soil on the carpet.

If I do find a crack- should is seal it with concrete/caulk and re-carpet and be vigilant about dehumidification? (Oct 7, 2014) Brennan

Reply:

Brennan

Radon gas does not leave black stains in buildings. That contractor friend is simply wrong.

But indeed radon gas moves upwards through points of air leakage in a building, so that might be behind his comment.

We see air bypass leak stains on carpets where there is air movement such as around floor HVAC registers or at a leaky wall-floor juncture. So that's at the edges not in the center of carpeting (unless there's an unusual air bypass leak in the center of the floor).

A couple of points to consider:

Most moisture meters, if we exclude thermal imaging, rely on measuring differences in electrical resistance to detect moisture.

See MOISTURE METER STUDY 

And thermal imaging itself relies on temperature differences. (For example a wet area or an area of air leakage will show up as cooler.)

See and THERMAL IMAGING, THERMOGRAPHY

But other contaminants or materials can also decrease resistance in an area of building material.

So not every reading variation is necessarily truly detecting moisture. Some attention, particularly looking for possible moisture sources, are key.

Both pin type moisture meters (Delmhorst for example) and electronic moisture meters (such as some Tramex meters) can be fooled by metal nearby: pipes, foil faced insulation, wiring.

Second: no moisture meter, nor thermal imaging device, can detect old leaks that have since dried, even though the leak might have initiated a building problem with rot, insect damage, or mold contamination.

This is why we argue that reliance on meters and imaging alone for water or mold detection are unreliable. But the instruments are indeed useful, in thoghtful hands. And neat too.

See THERMAL IMAGING, THERMOGRAPHY

and be sure to review the carpet stain causes

at CARPET STAIN DIAGNOSIS 

Brennan said: Salt from pet urine can also draw moisture from the air

Thanks for your comment. One thought (using my science background) was that the moisture meter gives a high reading on what looks like an old dog urine stain (former owner had dog).

I had the thought that these left over salts and ions from the urine might act as a weak conductor and activate the moisture meter.

On the internet, it seems that carpet companies use moisture meters to find hidden pet stains, because the salt from the urine can draw moisture from the air (or even just the natural evaporation of the concrete slab).

So, thanks for your help. I tend to over-think things. I agree, it is a neat tool.

(mod) said:

Interesting Brennan, and thoughtful. I agree with the salts / ions theory for both of the reasons you offer.

It's not over-thinking. The more we understand the better we can find and fix or prevent aggravations. Thanks.

Ghosting Stains - Other Questions

Is condensation causing the ceiling stains?

I can relate to the lines and patches in the article and had began to question issues of condensation but still unsure why in that particular spot? One of the beams (joists) is wet / damp and there's tarnished markings on the plasterboard as seen in the attached picture.

The dark patches get darker from a hot shower which is the room next door. Before we started having hotter showers, we only noticed a yellow stain the bedroom next door. I'm just really confused at how to resolve this.

Would it be possible to confirm from the picture if this is thermal tracking or ghosting please? 2022-10-22 by Kelly

Mod reply:

@Kelly,

I can't make out a pattern in your photo. But certainly thermal tracking appears at regular intervals that mark the framing of the building. So if you see a concentrated stain area in some other shape it's probably from a different cause.

Remedy for correcting the dark rectangles on the ceiling and interior walls?

What is the remedy for correcting the dark rectangles on the ceiling and interior walls? 2022-09-16 by Marilyn Perry

Mod reply:

@Marilyn Perry,

Glad to help,

Just take a look at THERMAL TRACKING REMEDIES

and then don't hesitate to ask any follow-up questions you wish.

 

What causes thermal tracking?

What causes thermal tracking? 2021-05-08 by William Spade

Mod reply:

@William Spade,

Thank you for asking what causes thermal tracking. Since that's exactly the topic that's explained on the page above I went to take a look to see why you might ask me nevertheless. I see that you have to read a while to get to the point that we are leaving airborne particles on building surfaces in areas that are cooler and usually slightly more damp. A lot of the article is explaining why the stains appear in the pattern that they do because that's diagnostic.

 

This article was so helpful!

Thank you so much for the detailed explanation! I just discovered lines along the edges and corners of my 60+ year old home's ceilings (never painted since the house was built), and knew they weren't mold, but, didn't have an explanation, until I came across this page! Again, thanks SO much! 2023-03-20 by skaizun

Mod reply:

@skaizun,

Thanks for the nice feed-back. We've worked hard on this information for many years so we're really pleased when readers find it accurate, useful, and trusted. - Daniel F.